Various types of protective covers have been heretofore developed for covering piles or mounds of particulate material, such as salt, sand, grain and the like, from the effects of the weather while the material is in outside storage. An example of a cover for protecting a large quantity of particulate material from the elements when stored outside in an otherwise unprotected condition is disclosed in the Double et al U.S. Pat. No. 3,949,527. While the cover disclosed in the Double et al patent is capable of protecting the pile or mound of material covered thereby, it possessed a number of shortcomings. For example, in order to counteract the effects of aerodynamic lift, a large number of ballast weights, such as automobile tires, had to be distributed over the upper surface of the cover of the Double et al patent and connected to each other by an extensive network of longitudinally, laterally and radially extending lines or cables. These cables creased and abraided the cover, and frequently cut through it. The large number and distribution of ballast weights, and their connecting cable network, also rendered the cover construction disclosed in the Double et al patent difficult to install and maintain.
Examples of covers for protecting piles of dry material in bulk, such as grain, are likewise disclosed in the Winters U.S. Pat. No. 4,084,358 and Wunderwald et al U.S. Pat. No. 2,730,150. While the covers disclosed in these patents were capable of protecting small to medium sized piles of grain, they did not lend themselves to protecting large piles or mounds of particulate material, such as salt and sand in outside storage.
Easily erectable and collapsible covers have also been developed for protecting trees and bushes from frost. An example of such a cover is disclosed in the Barnes U.S. Pat. No. 1,600,749. The front preventive covering disclosed in the Barnes patent, while capable of temporarily protecting a tree from frost and while utilizing flexible material straps secured to converging, vertically extending members around the periphery of the cover, was not well suited to protect large mounds or piles of particulate material over long periods of time.